Honey and Its Antimicrobial Properties: A Function of a Single Component, or the Sum of Its Parts?

INTRODUCTION: Honey is known for exhibiting antibacterial properties, indicating its use as part of traditional medicine since the early ages. With the advent of antibiotic-resistant bacteria, the need for alternative antimicrobials has outpaced the actual development of novel, broad-spectrum antibiotics. Previous research has revolved around the sugar content of honey because its sweetness makes it an attractive food source. However, research assessing the protein and lipid components of honey is lagging behind that of its sugar counterpart. The goal of this investigation was to examine the antimicrobial properties of honey and to identify any distinct proteins or lipids. METHODS: In order to isolate individual peptides and lipids, the different samples of local and foreign-sourced honeys were dialyzed, and the resulting dialysate proteins were screened via gel electrophoresis (sodium dodecyl-sulfate polyacrylamide gel electrophoresis [SDS-PAGE]) with Coomassie blue and silver stain, while lipids were examined using thin layer chromatography (TLC). To assess antimicrobial potency, a series of Kirby-Bauer disc diffusion assays was performed on Mueller-Hinton agar using different types of raw honey with Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis. The process was then repeated using the peptide extracts from the dialyzed fractions of the honeys. RESULTS: The SDS-PAGE trials revealed repetitive promising protein bands across several gels below 75kDa with both Coomassie blue and silver staining. The TLC analysis of varying raw honey samples consistently demonstrated the presence of medium and long-chain fatty acids, likely in the range of C12-C14. In the disc diffusion assays, the greatest amount of inhibition was seen when the honeys were tested as a whole instead of its constituent parts. CONCLUSION: Instead of an individual component acting as the key to honey's action against bacteria, it appears there is a synergistic relationship amongst the sugars, proteins, and lipids that make each honey unique.

Scleral Lens-Induced Corneal Edema After Radial Keratotomy.

ABSTRACT: This case series examines the magnitude and regional variation in scleral lens-induced corneal edema in postradial keratotomy (RK) eyes. Scheimpflug imaging was used to measure corneal thickness across the central 6 mm before and after scleral lens wear in nine post-RK eyes (median age 64 years). Variations in corneal edema were examined as a function of distance from the corneal center (six 0.5-mm annuli) and from 0° to 360°. The median central corneal edema was 2.19% (interquartile range 1.03%-3.18%; P=0.02) and increased in magnitude and variability further from the central cornea (from 1.30% in the central 0-0.5 mm to 3.12% in the 2.5-3.0 mm midperiphery) (P=0.02). Scleral lens-induced corneal edema in post-RK eyes was greater in magnitude further from the corneal center and at the approximate location of corneal incisions.

Formation of 7-dehydrocholesterol-containing membrane rafts in vitro and in vivo, with relevance to the Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a recessive disease typified by 7-dehydrocholesterol (7DHC) accumulation and depletion of cholesterol. Because cholesterol is a primary component of detergent-resistant membrane domains ("rafts"), we examined the compatibility of 7DHC with raft formation. Liposomes containing bovine brain phosphatidylcholine, sphingomyelin, cerebrosides, and either cholesterol, 7DHC, or coprostanol (the latter being incompatible with raft formation) were prepared. 7DHC was indistinguishable from cholesterol in its ability to become incorporated into membrane rafts, as judged by physical and chemical criteria, whereas coprostanol did not form rafts. The in vivo compatibility of 7DHC with raft formation was evaluated in brains of rats treated with trans-1,4-bis(2-dichlorobenzylamino-ethyl)cyclohexane dihydrochloride (AY9944), which mimics the SLOS biochemical defect. 7DHC/cholesterol ratios in rafts and whole brains from AY9944-treated rats were similar, indicating comparable efficiency of 7DHC and cholesterol incorporation into brain rafts. In contrast, dolichol (a nonsterol isoprenoid incompatible with raft formation) was greatly depleted in brain rafts relative to whole brain. Although brain raft fractions prepared from AY9944-treated and control rats yielded similar sterol-protein ratios, their gel electrophoresis profiles exhibited multiple differences, suggesting that altered raft sterol composition perturbs raft protein content. These results are discussed in the context of the SLOS phenotype, particularly with regard to the associated central nervous system defects.